See how compounding builds over time
Enter a starting balance, a monthly contribution, an expected annual return, and a time period — the calculator shows your future value, how much is your own money, and how much is growth. The math is standard compound interest; every figure is shown so you can check it.
Here's why
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Growth by year
| Year | Balance | Your contributions | Growth |
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Assumptions & methodology
FV = P(1+i)n + PMT·((1+i)n−1)/i, monthly compounding (i = annual return ÷ 12, n = years × 12). Contributions at end of each month. Constant return — real markets fluctuate. Nominal (before inflation); taxes and fees not included unless you model them separately.
Protect the growth you just saw: try Fee Drag or see Rule of 72 for a quick doubling estimate.
Explained in: How to Invest Your First $1,000 in Index Funds — the article this calculator's math comes from.
Education, not advice: This tool is for education only and is not personalized financial advice. It assumes a constant rate of return, which does not happen in real markets. Investing involves risk, including loss of principal. Past performance does not guarantee future results.